The recommended solution strategy to model an inductively coupled plasmas with RF bias is as follows. First solve the problem with inductively coupled plasma only using the Plasma, Time Periodic interface. To speed up this study set the Number of elements in the Extra Dimension Settings to 1. Since there is no RF bias applied yet it is not needed to have resolution along the period. After, add a second study that uses the solution of the previous study as initial conditions. Increase the Number of elements to 30-50 and use the Auxiliary sweep to ramp up the amplitude of the applied voltage.